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Physiology Year 1 > Week 2 > Flashcards

Week 2 Flashcards

1
Q

How thick is the alveolar wall?

A

Between 0.2 and 2.5 microns thick

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2
Q

what percentage of the atmostphere is oxygen?

A

20.93

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3
Q

what percentage of the atmoshere is carbon dioxide?

A

0.03

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4
Q

what percentage of the atmosphere is oxygen?

A

20.93

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5
Q

what is dalton’s law?

A

the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases in the mixture

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6
Q

how to work out partial pressure

A

percentage of gas in atmosphere x total pressure (760mmHg at sea level)

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7
Q

what is henry’s law?

A

gases dissolve in iquids in proportion to partial pressure

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8
Q

gases dissolve in liquids but depend on specific things incuding partial pressure - what else?

A

specific fluid medium, temperature.
solubility of a substance in blood is constant at a given temperature

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9
Q

what is the partial pressure of oxygen at the alveolus?

A

105

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10
Q

what is the partial pressure of oxygen at the capillaries (venous blood)

A

40

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11
Q

what is the percenage of carbon dioxide at the alveolus?

A

40

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12
Q

what is the partial pressure of carbon dioxide at the capillaries (venous blood)?

A

45

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13
Q

what is the most important factor for determining gas exchange?

A

partial pressure gradient

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14
Q

what is the a.v. O2 difference?

A

the difference between the arterial and venous oxygen levels.

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15
Q

what does the a.v. O2 difference impact?

A

the ability of your muscles to extract oxygen and use it,
as extraction increases, venous oxygen level decreases and a.v. O2 difference increases

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16
Q

what is the arterial oxygen content?

A

20/100ml blood

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17
Q

what is the venous oxygen content at rest?

A

15-16ml/100ml

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18
Q

what is the venous oxyge content during exercise?

A

4-5ml/100ml blood

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19
Q

what percentage of oxygen is bound to haemoglobin in the blood?

A

98

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20
Q

how many oxygen molecules does a fully saturated haeoglobin molecule carry?

A

4

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21
Q

is oxygen or carbon dioxide more solule?

A

carbon dioxide

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22
Q

how does a small decrease in the partial pressure of oxygen affect oxygen saturation?

A

fairly significant decrease in saturation

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23
Q

how do temperature and partial pressure of CO2 affect oxygen deloading?

A

oxygen is offloaded at a higher partial pressure

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24
Q

what is the bohr shift?

A

the graph (of PO2 and haemoglobin saturation) shifts to the right when pCO2 and temperature increase

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25
Q

How is CO2 carried in the blood?

A

as bicarbonate ions (70%), dissolved in plasma (10%), bound to harmoglobin as carbaminohaemoglobin (20%).

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26
Q

what is the importance of carrying carbon dioxde as bicarbonate ions?

A

helps control our acid-base balance

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27
Q

how do bicarbonate ions help control the acid-base balance?

A

CO2 and water form carbonic acid (H2CO3), this occurs in red blood cells and is catalysed by carbonic anhydrase
H2CO3 dissociated into bicarbonate ions and acid (HCO3 and H+). The H+ binds to haemoglobin, acting as a buffer and triggering the bohr effect

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28
Q

How does more CO2 mean O2 offloaded at a higher partial pressure?

A

More CO2 = more carbonic acid, so more H and then more H bound to haemoglobin so more O2 offloaded

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29
Q

what is cardiac output?

A

volume of blood ejected by the heart in one minute
Carduac output = HR x SV

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30
Q

What is cardiac output at rest?

A

HR = 70bpm, SV = 70ml, cardiac output = approx 5litres

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31
Q

what is stroke volume?

A

volume of blood ejected from the heart each beat

32
Q

what is stroke volume during maximal exercie?

A

150-160ml

33
Q

what is stroke volume dependent on?

A

end diastolic volume (preload)
strenght of the ventricular contraction (contractility)
average aortic blood pressure (afterload)

34
Q

what is frank stirling law?

A

SV increases in response to an increase in EDV due to a stretch in the ventricles which causes greater contraction, depends on venous return.

35
Q

what influences venous return?

A

how much your muscles act as a respiratory pump, valves in veins and vasoconstriction.

36
Q

how is the respiratory pump created during exericse?

A

you are squeezing your abdominal muscles creating high pressure, but thoracic cavity is expanding creating low pressure.

37
Q

what is the fick equation?

A

cardiac output = volume oxygen consumption in lungs / a.v. O2 difference

38
Q

what would the most accurate measure of a.v. O2 difference be?

A

measurement from pulmonary artery (venous system) and left atrium or aorta (aoritc system). this would be impossible, so peripheral artery is used instead e.g. wrist.

39
Q

what is extrinsic innervation?

A

autonomic control of the myocardium (heart)

40
Q

where does the parasympathetic impulse travel down?

A

vagus nerve

41
Q

what does the vagus nerve do? - consequential impact

A

release a neurotransmitter acetylcholine, affecteng the SA node, AV node and atrial myocardium. results in SA depolarisation (bradycardia) - decreasing heart rate.

42
Q

where does the sympathetic impulse travel down?

A

cardiac acceleratory nerves

43
Q

what does the sympathetic impulse cause?

A

adrenal medulla to release catecholamines (adrenaline and noradrenaline). affects SA, AV nad atrial and ventricular myocardium - results in increase in depolarisation (tachycardia), increase in SV, HR.

44
Q

what is the positive ionotropic effect?

A

increase in contractility

45
Q

what is anticipatory rise?

A

an increase in heart rate before exercise even if resting, in preparation for exercise.

46
Q

why does anticipatory rise occur?

A

central command withdraws parasympathetic impulses until HR is about 100bpm. further increase is then due to symapthetic impulses.

47
Q

why does HR decrease rapidly after exercise?

A

parasympathetic system is started again and muscle proprioceptors are not feeding back. mrore gradual as sympathetic system still involved not stopped completely

48
Q

tachycardia vs bradycardia

A

tachycardia - RHR above 100bpm, bradycardia - RHR below 60bpm

49
Q

why is RHR important?

A

for every increase of 10bpm in RHR there is a 9% increase risk of mortality and an 8% increase in risk of cardiovascular mortality.

50
Q

what is heart rate variability?

A

looks at ratio of sympathetic to parasympathetic nervous system.

51
Q

how is heart rate variability used?

A

in recovery - as an indicator of possible further arrests
in sport - overtraining usually causes a drop in HR variability

52
Q

what is a normal heart rate recovery?

A

greater than 22bpm.

53
Q

what is an abormal heart rate recovery?

A

anything less than 12bpm.

54
Q

how is heart rate used to set training zones?

A

of max HR
maximum - 90-100%
hard - 80-90%
moderate - 70-80%
light - 60-70%
very light - 50-60%

55
Q

what is the most accurate way to get a max heart rate value?

A

VO2 max test

56
Q

P wave

A

atrial systole and ventricular diasole continues

57
Q

QRS complex

A

ventricular systole and atrial diastole start

58
Q

T wave

A

atrial diastole continue, ventricular diastole starts at end of wave

59
Q

how to identify angina from an ECG

A

a fall in hte line between S and T

60
Q

what does an echocardiogram look at?

A

mechanical control of the heart - wall thickness, valve function ad ejection fraction (how much blood is ejecting)

61
Q

systole

A

heart contracting

62
Q

diastole

A

heart relaxing

63
Q

pulse pressure

A

systolic blood pressure - diastolic blood pressure
issues if over 70 (wide)

64
Q

mean arterial pressure

A

diastolic blood pressure + (pulse pressure/3).

65
Q

what looks at internal and energy demands placed on the heart?

A

rate pressure produced = systolic blood pressure x heart rate

66
Q

blood pressure equation

A

cadiac output x peripheral resistance

67
Q

what affects stroke volume?

A

venous return, muscle pump, respiratory pump, valves, frank stirling law, blood volume

68
Q

what affects heart rate?

A

sypathetic vs parasympathetic
receptors feeding into the control centre, temperature, adrenaline

69
Q

what affects peripheral resistance?

A

vessal diameter, blood viscosity, total vessel length

70
Q

what is the RAAS system?

A

renin-angiotensin-aldosterone system

71
Q

what does the RAAS system reduce?

A

blood pressure

72
Q

describe the RAAS system

A

kidneys notice drop in blood pressure and release renin, liver releases angiotensin. renin converts a to A I, angiotensin converting enzyme is released converting A I into A II.

73
Q

How does angiotensin II reduce blood [ressure?

A

increasing sympathetic activity - increasing HR
Kidneys retain more salt and increase K excretion, increases water retention&raquo_space; increasing blood volume and pressure
vasoconstriction of arterioles
pituitary gland releases ADH

74
Q

What can be taken if RAAS system is faulty?

A

ACE (angiotensin converting enzyme) inhibitors so the angiotensin I is not converted.

75
Q

how does exercise effect blood vessels?

A

endothelial cells in the lining release nitric ocide, a vasodilator, increasing the diameter of the lumen, decreasing blood pressure.

76
Q

how is blood pressure reduced during exercise?

A

nitric oxide - vasodilatory
Atrial natriuretic peptide (ANP) reduces renin release
hypothalamus and pituitary reduce release of ADH
drop in aldosterone from adrenal cortex, stopping absorption of water

Physiology Year 1 (4 decks)

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